Description
Fc gamma RIIB is a low affinity receptor that recognizes the Fc portion of IgG. The human CD32 group consists of Fc gamma RIIA, Fc gamma RIIB, and Fc gamma RIIC proteins that share 94-99% sequence identity in their extracellular domains but differ substantially in their transmembrane and cytoplasmic domains. Fc gamma RII protein is expressed on cells of both myeloid and lymphoid lineages as well as on cells of non-hematopoietic origin. Fc gamma RIIB has an intrinsic cytoplasmic immunoreceptor tyrosine-based inhibitory motif (ITIM) and delivers an inhibitory signal upon ligand binding. Ligation of Fc gamma RIIB on B cells down-regulates antibody production and in some circumstances may promote apoptosis. Co-ligation of Fc gamma RIIB on dendritic cells inhibits maturation and blocks cell activation. Fc gamma RIIB may also be a target for monoclonal antibody therapy for malignancies. Fc gamma RIIB plays an important negative-regulating role through modulating the signals from activation receptors